I will try and make a list of things needed to be a self employed contractor.
Dsc 1
Dsc 2
Deer management qualification
Quad ticket
Firearms ticket
Driving license
First aid
Register as a food business
Insurance (trade not the stuff you get as a member of a shooting organization)
Register as a business (remember you have to pay tax on any profit. )
You need a accountant if you are not willing to do it yourself.
Rifle
2nd spare rifle
Scope ( recommend a day night one in England remember your not there for sport or fun?
Mounts
Thermal
Sticks
4x4 truck
Trailer
Quad ( with insurance)
Chiller with painted floor, sink
Larder equipment
Rail system
Electric hoist
You have to build a big network of contacts to even get a look in on the contracts.
You have to build a relationship with multiple venison outlets and produce a perfect carcass every time. (this is very important it will generate a big proportion of your income.
There are lots of small things as well but I think this is a good start.